1. Field of the Invention
The present invention relates to a method for producing a liquid discharge head for discharging liquid as flying liquid droplet and depositing such liquid droplet on a recording medium thereby forming a record, a liquid discharge head produced by such method, a head cartridge and a liquid discharge recording apparatus equipped with such liquid discharge head.
The present invention also relates to a method for producing a liquid discharge head applicable to a printer for recording on recording media such as paper, fiber, yarn, fabrics, leather, metal, plastics, glass, timber, ceramics etc., a copying machine, a facsimile apparatus provided with a communication system, a word processor provided with a printer unit etc., and an industrial recording apparatus combined in complex manner with various processing apparatus, a liquid discharge head produced by such method, a head cartridge and a liquid discharge recording apparatus equipped with such liquid discharge head.
In the present invention, the word xe2x80x9crecordingxe2x80x9d not only means formation of a meaningful image such as a character or graphics but also formation of a meaningless image such as a pattern.
The present invention further relates to a method for producing a silicon plate having a functional unit, and a silicon plate produced by such producing method.
2. Related Background Art
For improving dot placement accuracy of the liquid droplet by an ink jet head which is a liquid discharge head, there has conventionally employed a tapered orifice which is thicker in the base portion at the liquid chamber side and thinner in the front end portion at the discharge port side, with a cross section gradually decreasing toward the front end portion. For forming such tapered orifice on an orifice plate, there has been employed, for example, electroforming on a nickel sheet, hole formation on a resin sheet with an excimer laser and hole formation on a stainless steel sheet by pressing.
Also the European Patent Laid-Open No. 921004 discloses the use of silicon (Si) for the orifice plate of the ink jet head. The specification of this patent describes formation of an orifice plate consisting of silicon and having discharge orifices, by grinding a silicon plate in which penetrating holes are formed into a thickness of 10 to 150 xcexcm. For forming such discharge orifices, there are described a method of ion beam working (in vacuum), excimer laser working and etching (dry etching or wet etching).
Also for silicon material, the U.S. Pat. No. 5,498,312 discloses a technology of executing plasma etching introducing a mixture of etching gas such as SF6, CF4 or NF3 and passivating gas such as CHF3, C2F4, C2F6, C2H2F2 or C4H8 into a chamber and employing a plasma density of 1012 ion/cm3 or higher and an energy range of 1 to 4 eV in order to increase the etching rate and avoiding the drawback of masking.
However, the above-described method for producing the orifice plate for the ink jet head utilizing silicon, disclosed in the aforementioned European Patent Laid-Open No. 921004 involves a step of preparing a silicon plate thicker than the predetermined thickness of the orifice plate and penetrating such silicon plate, and is therefore relatively time-consuming, so that there is still a room for the improvement in the mass producivility.
Also in case of etching of the silicon plate with the method described in the aforementioned U.S. Pat. No. 5,498,312, the depth of the etched hole is little controllable and the fluctuation in the etched depth, resulting from the fluctuation in the material constituting the silicon plate, cannot be controlled, so that it is difficult to form the holes with satisfactory precision.
In consideration of the foregoing, a principal object of the present invention is to provide a novel method excellent in mass producibility capable of forming penetrating holes of a uniform shape in plural units at the same time, without being affected by the fluctuation in the crystal structure of silicon.
In another aspect of the present invention, in case a silicon plate in which penetrating holes are formed is to be used as the orifice plate or as a filter for preventing dust intrusion in the ink jet head, the interior of such penetrating hole comes into contact with the liquid. Since it is difficult to form a film in the interior of the penetrating hole, there cannot be used certain liquid such as strongly alkaline liquid.
Therefore, another object of the present invention is to provide a silicon plate in which the interior of the penetrating hole is not etched even in contact with the liquid which tends to etch silicon.
Still another object of the present invention is to provide a method, in case of producing a liquid discharge head with an orifice plate consisting of silicon which is same as that constituting an element substrate bearing a thermal energy generating element, capable of producing a liquid discharge head of a long dimension with satisfactory reliability, a liquid discharge head produced by such method, a liquid discharge head cartridge and a liquid discharge recording apparatus utilizing such liquid discharge head. Still another object of the present invention is to provide a method for producing a liquid discharge head, capable of realizing an assembling method enabling alignment not only of a single nozzle array but also of plural nozzle arrays.
The principal features of the present invention, for attaining the above-mentioned objects, are as follows.
The present invention provides a method for producing a liquid discharge head provided with plural energy generation elements for generating energy for discharging liquid as a flying liquid droplet, a head main body having plural liquid flow paths in which the energy generation elements are respectively provided, and an orifice plate having plural discharge ports respectively communicating with the liquid flow paths wherein the orifice plate and the head main body are mutually adjoined, the method comprising a step of preparing a substrate of a silicon-containing material for producing the orifice plate, a step of forming, in positions on the surface of the substrate corresponding to the discharge ports, plural recesses of the depth larger by 5 to 50 xcexcm than the depth of the discharge ports by dry etching, a step of thinning the substrate from the rear surface side opposite to the above-mentioned surface until the depth of the recesses becomes equal to that of the discharge ports to form plural discharge ports on the substrate thereby obtaining the orifice plate on which the plural discharge ports are formed, and a step of adjoining the orifice plate to the head main body.
The present invention is also featured by a method for producing the liquid discharge head according to the foregoing, wherein the dry etching is executed by repeating etching with any one of SF6, CF4 and NF3 gas and forming fluorine-containing polymer on the lateral wall with any one of CHF3, C2F4, C2F6, C2H2F2 and C4H8 gas.
Furthermore, it is preferred that, in the aforementioned step of forming the plural recesses by dry etching, the discharge port is so shaped as to have the cross sectional area gradually decreasing from the side of the aforementioned liquid flow path to the front end side of the discharge port and as to have a region in which the cross sectional area is constant, and that the respective recess is so shaped by dry etching as that the discharge port is opened in such region.
Furthermore, it is preferred that the aforementioned step of thinning the substrate is executed by at least either of grinding, polishing and etching.
Furthermore, the mentioned preferably comprises further, after the formation of the plural recesses on the substrate, a step of forming a protective film in a portion of the substrate coming into contact with the ink.
Furthermore, the method preferably comprises further, after the step of adjoining the orifice plate to the head main body, a step of coating ink-resistant resin on a surface having discharge ports.
Furthermore, the method preferably comprises further a step of filing resin or metal in the recesses, after the aforementioned step of forming the recesses or after the step of forming the protective film and before the step of thinning the substrate, and a step of removing the filled resin or metal after the thinning of the substrate.
Furthermore, the method preferably comprises further a step of applying a UV peelable tape on the surface of the substrate in order to maintain the strength of the substrate at the grinding or polishing thereof, after the aforementioned step of forming the recesses or after the step of forming the protective film or after the step of filling resin or metal in the recesses and before the step of thinning the substrate, and a step of removing the UV peelable tape after the step of thinning of the substrate.
Furthermore, the method preferably comprises further a step of applying a UV peelable tape on the surface of the substrate in order to maintain to a certain extent the strength of the substrate at the grinding or polishing thereof, after the aforementioned step of forming the protective film and before the step of thinning the substrate, and a step of forming a projection by dry etching around the discharge port at the adjoining side of the orifice plate, before the formation of the recesses, in order to form a projection to enter into and engage with the liquid flow path.
Furthermore, it is preferred that the aforementioned step of forming the protective film on the substrate forms the protective film on the entire internal wall of the recesses and the method preferably comprises further, after the aforementioned step of thinning the substrate in order to form the plural recesses in the substrate, a step of removing the surfacial layer of the substrate by wet etching to cause a part of the protective film, constituting the internal wall of the discharge port, to protrude from the surface of the substrate thereby forming the projection.
Furthermore, the method preferably comprises further, after the aforementioned step of causing a part of the protective film, formed on the internal wall of the discharge port, to protrude from the surface of the substrate, a step of forming a water-repellent film around the projection.
Furthermore, the method preferably comprises further, after the step of thinning the substrate, a step of adjoining a frame member consisting of silicon or glass for reinforcing the substrate, to the substrate by vacuum thermal adjoining, anodic adjoining or adhesive material.
Furthermore, it is preferred that the aforementioned frame member is to be adjoined around a portion of a surface, opposed to and adjoined to the head main body, of the substrate, and it is preferred that the aforementioned step of adjoining the orifice plate, bearing the adjoined frame member, to the head main body further includes a step of filling head-conductive resin in a gap between the head main body and the frame member so as to increase the adhesion strength of the head main body and the orifice plate while maintaining the thermal conductivity between the head main body adjoined to the orifice plate and the frame member.
Furthermore, it is preferred that the substrate, prepared in the aforementioned step of preparing the substrate consisting of the silicon-containing material, is a silicon wafer, that plural orifice plates are prepared from a silicon wafer, and that, in the aforementioned step of forming the plural recesses on the surface of the silicon wafer, groove-shaped plate dividing patterns are formed by dry etching together with the plural recesses on the surface of the silicon wafer, whereby the aforementioned step of thinning the silicon wafer from the reverse side devices the silicon wafer into plural orifice plates by the above-mentioned plate dividing patterns simultaneously with the formation of the discharge ports.
Furthermore, it is preferred that the aforementioned plate dividing patterns are formed excluding the external peripheral portion of the silicon wafer.
Furthermore, the present invention provides a liquid discharge head for discharging liquid utilizing bubble generation induced by applying thermal energy to the liquid, the head being produced by any of the foregoing producing methods.
Furthermore, the present invention provide a head cartridge comprising the aforementioned liquid discharge head and a liquid container, containing liquid to be supplied to the liquid discharge head.
Furthermore, the present invention provides a liquid discharge recording apparatus comprising any of the aforementioned liquid discharge heads, and drive signal supply means for supplying a drive signal for causing the liquid discharge head to discharge liquid.
Furthermore, the present invention provides a liquid discharge recording apparatus comprising any of the aforementioned liquid discharge heads, and recording medium conveying means for conveying a recording medium for receiving the liquid discharged from the liquid discharge head.
Such liquid discharge recording apparatus is to execute recording by discharging liquid from the liquid discharge head and depositing such liquid onto the recording medium.